Early on during a Celta course – the initial teacher training certificate offered by Cambridge Esol – the instructor is likely to give trainees a taste of communicative language learning by teaching them the equivalent of "My name is ..." and "What is your name?" in a suitably obscure foreign language.

The aim of the exercise is not to make trainees more polyglot, but to give them an insight into the emotions that adults experience when they find themselves in a group of strangers and are asked to, in effect, make fools of themselves. As the trainees mangle pronunciation, forget a phrase repeated only moments before and wait nervously for their turn to speak in front of the class, they are getting an insight into the learner experience that should make them more intuitive and effective teachers when they enter the classroom for the first time.

This learning-by-doing approach has helped to establish the Certificate in English Language Teaching to Adults, to give it its full title, as a benchmark for the training of people who want to enter the ELT profession, but plans by Cambridge Esol to introduce a version of the Celta course that combines tutorials delivered online with face-to-face teaching practice is raising concerns that this "gold standard" could be undermined.

Cambridge Esol says that more than 10,000 people achieve the Celta each year after completing a minimum of 120 hours of tuition and teaching practice at over 250 approved training centres in 54 countries. Over the last six months it has been developing a "blended" version of the course with International House (IH) London, a leading centre for English language teacher training in the UK.

The course will be piloted by IH in London in early 2011. Participants will log on to a virtual learning environment (VLE) to access the "input" element of the course: presentations on teaching theory and practice totalling more than 100 hours of training delivered over a minimum of 10 weeks.

The other components of the course are identical to the standard Celta: trainees must complete six hours of observed teaching practice, at the IH centre, and observe experienced teachers for a further three hours.

According to Cambridge Esol, the new course is its response to a shift in the way people want to access training. Andrew Nye, head of stakeholder relations, says that the majority of Celta courses are delivered over an intensive four- or five-week period, and some participants want a more flexible option. "The point is to broaden access to Celta and to make it more attractive to people who don't have four weeks of their life to give up. A number of people will benefit from that and the additional convenience," Nye said.

Candidates who successfully complete the online Celta will receive the same certification as their fully "face-to-face" counterparts. But will trainees come away from the blended version with the same breadth of experience, in particular the firsthand exposure to classroom-based training?

Advocates of the current Celta format argue that people who have had no previous exposure to a teaching environment can learn a great deal from being part of a face-to-face course over an extended period, especially class dynamics – what it feels like to work collaboratively, speaking in front of peers. These are all essential elements of communicative teaching.

The response from Cambridge Esol is that the online elements of the course have been designed to replicate those opportunities to observe teaching styles. Nick Charge, assistant director for assessment, says that the functionality of the VLE and the special training that will be given to tutors will compensate for the lack on in-class training sessions.

"We are producing online materials that we think will enable participants to understand the basic principles of teaching and apply them. There are a lot of video clips of lessons built into the course which will allow trainees to watch people doing things. When they work through tasks and activities trainees will be asked to reflect on the way they were set up and the way they were presented to them," Charge said.

As director of education for the OISE group of language schools, which employs more than 1,000 teachers in the UK, Geoff Hardy-Gould is likely to be employing the future products of the online Celta. He says he is positive about the new course, but acknowledges that there will be challenges.

He says the VLE system that Cambridge Esol is planning to use can offer a rich training environment through the use of video and with the scope to focus on details of course content.

"But you do lose the tutor modelling how to teach," he said. "In a face-to-face environment the trainer can quickly demonstrate a way of doing something, for example checking understanding among a group of learners."